124 results about "Coalbed methane extraction" patented technology

The invention belongs to the technical field of coal bed gas mining, and particularly discloses a multi-coal-bed mining optimization control method based on crossheading position stability, and the method comprises the steps: comprehensively obtaining parameters such as coal bed spacing, thickness, inclination angle, roof and floor lithology and fault distribution, and generating an accurate three-dimensional geologic model through three-dimensional modeling software; and the condition of incomplete geological analysis of a traditional method is changed. And on the aspect of crossheading arrangement, empirical operation is replaced with finite element analysis, the anchor rod distance and the support density are accurately determined, and safety and economical efficiency are improved. The mining sequence planning is changed from dependence on a fixed rule to establishment of an identification model combined with a genetic algorithm, and dynamic optimization is realized. The mining height, the mining width and the advancing speed are flexibly regulated and controlled according to the mapping relation table in the mining process, and real-time dynamic adjustment is achieved. Meanwhile, the early warning mechanism calculates scores based on crossheading stress data, is more accurate and sensitive, and has higher pertinence and effectiveness.

The invention provides coal seam multi-section type directional fracturing and permeation increasing equipment and method, and relates to the technical field of coal mine gas treatment and coal seam gas exploitation, the coal seam multi-section type directional fracturing and permeation increasing equipment comprises a machine body, a propelling mechanism, a fracturing pipe and a liquid inlet mechanism, and a plurality of sets of directional assemblies are arranged outside the fracturing pipe at equal intervals; and the fixing mechanism is used for directionally spraying the high-pressure water to the fixed direction in the coal seam and comprises a limiting component arranged on the propelling mechanism and used for limiting the fracturing pipe stretching into the fracturing seam and a connecting component arranged on the limiting component and used for locking the fracturing pipe. High-pressure water can be directionally jetted to the fixed direction in a coal seam fracturing hole, the situation that due to the fact that the high-pressure water is jetted at will, a large number of cracks are generated on the soft portion of the coal seam, and consequently permeation increasing is uneven is avoided, in addition, a fracturing pipe stretching into the fracturing hole can be fixed, and the situation that the permeation increasing effect is affected due to the fact that the fracturing pipe shakes when equipment runs is avoided.

The invention belongs to the technical field of coal bed gas exploitation, and particularly relates to an extraction system and method for high-pressure air blasting and hot flue gas displacement of coal bed gas. The system comprises a high-pressure air blasting unit, a hot flue gas injection unit, a gas extraction unit and a data monitoring unit, the high-pressure air blasting unit and the hot flue gas injection unit share the same blasting and gas injection well, an extraction well is arranged on the outer ring of the blasting and gas injection well, and the gas extraction unit extracts gas through the extraction well; the coal seam is subjected to fracturing and permeability increasing through high-pressure air blasting, the coal seam can be effectively fractured, and the permeability of the coal seam can be effectively improved; hot flue gas is injected after high-pressure air blasting permeability increasing is conducted on the coal seam, the hot flue gas can be smoothly injected into the coal seam, and the coal seam is further fractured; the temperature of the coal seam can be increased by injecting the hot flue gas, desorption and migration of CH4 are facilitated, meanwhile, CH4 in an adsorption state is replaced by CO2 by means of the adsorption characteristic of CO2, and CO2 is effectively sealed in the coal seam while the desorption amount of the coal seam gas is increased.

The invention relates to a condensate-oil-resistant and temperature-resistant foam scrubbing agent for deep coal bed gas exploitation and a preparation method of the condensate-oil-resistant and temperature-resistant foam scrubbing agent. The method comprises the following steps: (1) mixing 45-55 parts of sodium 3-chloro-2-hydroxypropanesulfonate and 14-28 parts of lauryl sodium sulfate, dissolving in an aqueous solution containing a special additive, adding 70-110 parts of aliphatic tertiary amine, heating to dissolve the aliphatic tertiary amine, adding the mixed solution into a three-neck flask, adjusting the pH value, heating, adjusting the pH value once every 25-35 minutes, reacting at 70-90 DEG C for 6-8 hours, and cooling to obtain a reaction solution; obtaining a yellow viscous product, namely the long-chain fat hydroxypropyl sulfonated betaine; and (2) adding 5-10 parts of a mixture of polyacrylamide and cellulose and 1-8 parts of nanoparticles into 80-150 parts of a product obtained in the step (1) to obtain the condensate oil-resistant temperature-resistant foam scrubbing agent. The lowest surface tension of the foam scrubbing agent can reach 28.12 mN / m, the foam scrubbing agent is high in foaming capacity, the foam height in clear water can reach 980 mL, the half-life period in high condensate oil content can reach 350 s, the condensate oil content reaches 35%, the foam height can still reach 750 mL, and the liquid carrying rate can reach 83.2%.

The invention discloses a method for enhancing coalbed methane recovery efficiency by an external magnetic field, which comprises the following steps of: arranging a plurality of electrified coils or magnetic field generators connected with a power supply in a coalbed to generate an alternating magnetic field in the coalbed; cH4 molecules show diamagnetism under the action of a magnetic field, a repulsive effect is generated in a coal seam, and the adsorption effect of CH4 and a coal body is weakened; and on the other hand, as the coal body contains ferromagnetic or paramagnetic minerals, the alternating magnetic field excites the annular eddy current in the coal body through electromagnetic induction so as to generate Joule heat. Therefore, coal matrix expansion and microfracture expansion can be induced by temperature rise of the coal body, the permeability of the coal body is further improved, and more channels are provided for CH4 desorption and flowing; the clean, efficient and environment-friendly coal bed gas exploitation method is provided on the basis of superposition of multiple production increasing mechanisms, and a new technical approach is provided for exploration and development of unconventional oil and gas resources.

The invention discloses a soft coal seam nanofluid fracturing propping material and a preparation method thereof.The soft coal seam nanofluid fracturing propping material is prepared from, by weight, 80-90% of a base material, 1-5% of a super-hydrophobic coating, 5-10% of a catalytic active component and 5-15% of a rheological enhancer, the base material is a compound of high-purity silicon dioxide nanoparticles and graphene nanosheets GNP, the particle size of the high-purity silicon dioxide nanoparticles is 50-200 nm, the super-hydrophobic coating is a fluorosilane modified layer, the thickness of the super-hydrophobic coating is 5-20 nm, and the invention relates to the technical field of coal bed gas exploitation. According to the soft coal seam nanofluid fracturing propping material and the preparation method thereof, the surface of the material is provided with a super-hydrophobic coating, friction force with a coal matrix is reduced, high embedding resistance is achieved, the flow conductivity is specifically enhanced, an extra flow channel is provided through a porous nanostructure, the fracturing fluid permeability is improved, and meanwhile gas desorption can be cooperated; catalytic active sites are introduced to the surface of the material to promote adsorption and diffusion of methane molecules.

The invention belongs to the technical field of coal bed gas exploitation and carbon dioxide geological storage, and relates to a coal bed carbon dioxide injectability evolution whole process simulation device and method, and the device comprises a true triaxial stress loading system, a temperature control system, a multi-mode gas injection system, a monitoring system, and a data processing system. The deep stratum stress state and the stratum temperature field are simulated, constant-pressure and constant-current mode carbon dioxide is injected into the true triaxial stress loading system to carry out groutability attenuation and recovery simulation, and nitrogen and pulse mode injection is switched to carry out temperature change regulation and control, phase change regulation and control and frequency change regulation and control so as to simulate groutability improvement. According to the method, a whole-process evolution mechanism of attenuation-recovery-improvement of carbon dioxide groutability is realized, meanwhile, data acquisition and permeability and stress calculation are performed through a monitoring system and a data processing system, and rapid conversion from original data to core parameters is realized; and accurate experimental data support is provided for on-site injection parameter optimization and regulation and control technology research and development.

The invention discloses a coal bed gas exploitation and separation utilization method based on SCCO2 assistance, and belongs to the technical field of coal bed gas development. Supercritical carbon dioxide is prepared through a high-pressure reaction kettle and stored in a supercritical carbon dioxide storage and collection tank, meanwhile, nitrogen mixed with graphene is introduced, and CO2 / CH4 adsorption selectivity is enhanced by means of the characteristic that the specific surface area of graphene is large. A variable-frequency sound wave diffuser is matched to excite coal seam micro cracks through low-frequency sound waves, and supercritical carbon dioxide and nitrogen mixed gas is injected into a coal seam injection well. In the injection process, the sound wave diffuser synchronously radiates high-frequency sound waves to improve the displacement efficiency, then the gas enters the gas separation tower integrated with the molecular sieve membrane, and the produced gas is divided into upper methane, middle carbon dioxide and other bottom miscellaneous gas. Methane is pressurized by an air compressor and then stored in a methane storage tank, carbon dioxide is purified and pressurized and then recycled for coalbed methane exploitation, and offensive gas is cooled and stored after generating power by a steam turbine. And efficient mining, separation and multi-path utilization of the coal bed gas are realized.

The invention relates to the technical field of oil and gas field and coal bed gas exploitation engineering, in particular to an underground gas-water two-phase jet flow drainage and mining device and a using method. According to the technical scheme, more than one group of leather cups are arranged on the outer wall of the lower side of a hydraulic pump body, and the upper end of the hydraulic pump body is connected with the lower end of a pneumatic pump body through an upper connector of the hydraulic pump; an air distributing and collecting umbrella pipe is installed on the outer side of the pneumatic pump body, a pneumatic throat pipe, a liquid drop micronizer and a pneumatic nozzle are arranged in the pneumatic pump body, a pneumatic diffusion cavity is formed in the upper portion of the pneumatic throat pipe, the pneumatic nozzle is arranged on the lower portion of the pneumatic throat pipe, the liquid drop micronizer is arranged on the upper side of the pneumatic throat pipe, and the lower end of the pneumatic nozzle is connected with an air inlet. The upper end of the pneumatic nozzle is communicated with the mixed liquid channel. The hydraulic pump has the advantages that the hydraulic pump body and the pneumatic pump body are designed to be integrated into an organic whole, the structure is compact and novel, high-pressure water jet speed-increasing atomized liquid flow and high-pressure gas jet flow are integrated to achieve jet flow drainage and mining, the lifting lift is greatly improved, and the negative-pressure suction and plug removal effects are also achieved on other blockages in a production layer.

The application discloses a method for exploiting coalbed methane by using a horizontal well group in a coal reservoir with an underpressure type, which comprises the following steps: arranging a horizontal well group, the horizontal well group comprising a predetermined number of horizontal wells, each horizontal well comprising a horizontal well section, and each horizontal well section being located in a coal reservoir of the same layer system; dividing each horizontal well section into a plurality of fracturing sections with a predetermined length, perforating a perforation position in each fracturing section to form a fracturing point; performing fracturing construction on each fracturing section, the fracturing construction comprising a liquid injection and energy storage fracturing stage and a main fracturing stage, in the liquid injection and energy storage fracturing stage, a first part of liquid is injected into the coal reservoir through the fracturing point at a predetermined discharge capacity and a predetermined construction pressure to fill natural fractures and cleats of the coal reservoir, in the main fracturing stage, a second part of liquid is injected into the coal reservoir through the fracturing point to form artificial fractures in the coal reservoir, and the predetermined construction pressure is not higher than a formation fracture pressure of a region where the horizontal well group is located; and after all the fracturing sections complete fracturing, coalbed methane exploitation is performed.

The utility model relates to the technical field of coal bed gas exploitation, and discloses a coal bed gas ground well fracturing and yield increasing device which comprises fracturing main body units, fracturing device connecting pieces, variable connecting pieces, a drainage pipe, a hole sealing device and a cable, the fracturing device connecting pieces are installed between the fracturing main body units, the variable connecting pieces are installed at the upper ends and the lower ends of the fracturing main body units, and the drainage pipe is installed between the fracturing main body units. The drainage pipe is installed on the surface of the variable connecting piece, the hole sealing device is installed on the surface of the drainage pipe, and the cable is electrically connected to the fracturing body unit. The coal bed gas ground well fracturing yield increasing device is convenient, stable, safe and efficient for the CO2 fracturing coal bed gas control technology, the direct acting radius of the CO2 fracturing technology is 1.5-5 m, the influence radius can reach 15 m, the gas extraction drilling work amount is reduced by 30%-60%, the duration time of high-concentration and large-flow gas extraction is long, the gas extraction lower limit is effectively reduced, and the gas extraction efficiency is improved. The method is suitable for coal seams with different firmness coefficients, and has a better application effect in coal seams with strong gas adsorbability.

The invention is suitable for the technical field of coal bed gas exploitation safety, and provides an underground coal bed gas collection monitoring and safety early warning method and system, and the method comprises the steps: obtaining the state parameters of a target region, and building a comprehensive gas diffusion analysis model covering the internal space of a pipeline, a coal bed crack and an underground roadway; simulating gas flow and concentration change based on the model, and generating a first installation scheme of the pipeline sensor; in combination with coal seam geology and ventilation parameters, simulating a coal seam gas dissipation direction and a convergence area, and generating a second installation scheme including acquisition equipment arrangement; and a real-time data transmission network is constructed, abnormal data are identified through space-time correlation analysis, equipment faults and real leakage are distinguished, and early warning is performed. The system corresponds to the method. According to the method, the monitoring layout is optimized through the comprehensive model, the anomaly recognition precision is improved, comprehensive and accurate safety early warning is achieved, and the mining safety of underground coal bed gas is guaranteed.

The utility model relates to the technical field of coal gas mining equipment, and discloses an underground coal bed gas mining and desanding device, a top gas pipeline is arranged at the top of a bottom gas pipeline, a desanding and water filtering assembly is arranged between the bottom gas pipeline and the top gas pipeline, and a desanding and water filtering assembly is arranged between the bottom gas pipeline and the top gas pipeline. The desanding and water filtering assembly is arranged between the bottom gas conveying pipeline and the top gas conveying pipeline, the desanding net barrel in the desanding and water filtering assembly can filter large-particle sand contained in conveyed coal gas, and the dust filtering net can filter fine dust again. After activated aluminum oxide powder is filled in the aluminum oxide storage net cylinder, water molecules contained in the coal gas passing through the aluminum oxide storage net cylinder can be adsorbed and removed, so that water and gravel particles contained in the coal gas discharged outwards can be effectively removed and purified; water is prevented from being mixed with dust particles to adhere to the inner wall of the pipeline, and it is guaranteed that coal gas conveying is safer and more reliable.

The invention provides a multilateral well coalbed methane extraction method, which comprises the following steps of: selecting one coal seam with one or more coal seams with higher coalbed methane content above as an extraction coal seam, and arranging a dense rib multilateral well coalbed methane extraction system in the adjacent coal seam at the upper part before coal seam extraction work is propelled to the extraction coal seam, and then coal bed gas extraction is carried out. According to the extraction method, efficient extraction of the coal bed gas close to the coal seam and flowing of the coal bed gas (gas) into the goaf and the roadway are effectively achieved, and scientific guidance is provided for effectively implementing co-extraction of the coal gas in the thin-medium thick coal seam group.

This invention discloses a simulation device for gas and water production in coalbed methane fracturing wells, comprising a base, a support with an arc-shaped cross-section fixed on the base, a wellbore placed on the support, end cap assemblies connected to both ends of the wellbore, a vertical rod fixed to one side of the base, one end cap assembly hinged to the bottom of the vertical rod, a pulley at the top of the vertical rod with a rope wound around it, the rope connected to the end cap assembly at the end furthest from the vertical rod, and a winch at the lower end of the vertical rod for winding the rope. Compared with existing technologies, this invention fully considers the simulation requirements under different working conditions, providing researchers with a comprehensive and controllable experimental platform, facilitating in-depth research on various influencing factors in the coalbed methane fracturing process, and providing a more scientific theoretical basis and experimental evidence for coalbed methane extraction.

The present invention discloses a downhole screen with a self-cleaning function, comprising a screen body, a transmitting transducer, a flow sensor, a controller, and a power supply device disposed within the screen body. The transmitting transducer is disposed in the middle section of the screen body, its axis parallel to the axis of the screen. The flow sensor is disposed at one end of the screen body near the water outlet, and the controller is electrically connected to the transmitting transducer, flow sensor, and power supply device. This downhole screen can effectively clean impurities clogged between the screen wire wraps or slits, ensuring normal pump fluid supply, extending the pump inspection cycle, improving the pumping efficiency of oil and gas wells, and reducing coalbed methane extraction costs.

The utility model discloses a kind of deep coalbed gas exploitation sampling devices, including shell, the shell inside is provided with inner bag, the hollow inside the inner bag, top and bottom are separately provided with communicating pipe and sampling pipe, the communicating pipe and sampling pipe are respectively worn out shell and with shell sliding connection, the inner bag is slidably arranged with sealing plate, the sealing plate top is fixedly provided with connecting frame, the connecting frame top is penetrated by screw rod and is connected with screw rod, the connecting frame top is provided with recess and the recess is slidably connected with limit rod, the limit rod one end is fixedly connected with inner bag, the screw rod one end is connected with motor fixedly installed in inner bag inside, by setting sampling device in inner bag, put inner bag in shell to protect inner bag, and set spring for buffering between inner bag and shell to buffer external impact force, and by setting counterweight that can be disassembled between each other, it is convenient to adjust counterweight.

The present invention discloses a drilling-type coal seam in-situ gasification mining method, which belongs to the technical field of coal in-situ gasification and coalbed methane mining. Two vertical boreholes are constructed from the ground through the rock layer to the coal seam, and then horizontal boreholes are constructed at the bottom of the two vertical boreholes to communicate with each other. A combustion system is set in one borehole, and an extraction system is arranged in the other borehole; the combustion system includes a combustion pipe with multiple flame nozzles at the end. After the combustion pipe enters the end of the horizontal borehole, it is ignited and sprays fire into the coal seam, and the extraction system is started for extraction. At the same time, the combustion pipe moves along the horizontal borehole while burning until it reaches the other end of the horizontal borehole. The combustion pipe rotates slowly horizontally with the entrance end of the horizontal borehole as the center of the circle while continuously telescoping back and forth, forming a gasification goaf that is fan-shaped when viewed from the horizontal plane, and mining is stopped until the gasification goaf is close to forming a circle. Coal mining is directly changed to gas and water gas mining, achieving unmanned underground mining, reducing mining costs, and reducing waste ground emissions.

The present application relates to a kind of coalbed gas production prediction method and system based on data driving, first, the coalbed gas dynamic production history data of the predicted production well and the coalbed gas production prediction related data of the predicted production well are acquired;According to the coalbed gas dynamic production history data, the production well type to which the predicted production well belongs is determined;Then select the trained coalbed gas production prediction model corresponding to the production well type as target model;Finally, the coalbed gas production prediction related data of the predicted production well is input into the target model, and the production data of the predicted production well is obtained.The present application obtains the most easily obtained and the most valuable monitoring data in coalbed gas mining site, calculates the coalbed gas production according to this part of data and using the production prediction model trained by machine learning method, reduces the data acquisition time, and improves the coalbed gas production prediction speed.

The invention discloses a coal mine area coal bed gas full-time-domain extraction and coal gangue filling integrated method, and belongs to the technical field of coal bed gas development, ground gas control and mine solid waste disposal. Constructing a plurality of coalbed methane extraction wells with a three-opening well body structure in the coal mining preparation area, and pre-extracting coalbed methane of an exploited coalbed after high-pressure water jet well completion; before a working face is recovered to a coal-bed gas well, perforation is carried out on an overlying protected layer section, and pressure relief coal-bed gas extraction is carried out through stress release and permeability increasing effects generated by coal mining; and after the goaf is closed, coal bed gas released by coal walls and residual coal is extracted under negative pressure. And after extraction of the goaf is finished, goaf coal gangue grouting filling is conducted through the coal-bed gas well, coal gangue is absorbed, and the ground settlement amount is reduced. According to the method, the same coal-bed gas well is used for full-time-domain coal-bed gas extraction before mining, during mining and after mining and coal gangue goaf filling, the comprehensive cost of coal-bed gas development, gas control and mine solid waste disposal in a coal mine area can be remarkably reduced, and the method has safe, environmental and social benefits.

The present invention discloses a surface long-bore coal body internal combustion fluidized mining device and working method, relating to the technical field of coalbed methane mining and gas extraction. It comprises a combustion support system and a drainage system; it comprises an oxidizer tank, a reductant tank, and an igniter, as well as a combustion pipe and a drainage pipe that enter the coal seam borehole through the wellbore, with a flame head provided at the end of the combustion pipe; the drainage system comprises a heat exchanger and a water-gas separator connected to each other by pipelines, a valve provided on the pipeline, a refrigerant inlet and a refrigerant outlet provided on the heat exchanger, and an oil pump connected to the oil pump through a mixing pipe. The oil pump is connected to the drainage pipe, and the gas and water extracted by the oil pump enter the heat exchanger through the mixing pipe. The system utilizes the oxidizer and reductant to react and release heat in the coal seam borehole, igniting the coal in the coal seam, achieving continuous, stable, and controlled combustion of a portion of the coal body inside the borehole, thereby changing the underground mining mode of coal mines and achieving safe and green mining without the removal of waste rock from the mine and the need for personnel to go down the mine, which is of great significance.

The invention relates to the technical field of coal bed gas exploitation, and particularly discloses a device and a method for preventing and treating accumulated liquid in a coal bed gas pipeline. A liquid pumping mechanism is mounted at one end of the gas conveying pipeline, an adsorption mechanism is mounted at the other end of the gas conveying pipeline, and a gas-liquid separation mechanism is mounted on one side of the outer wall of the liquid pumping mechanism; through cooperative work of parts such as the liquid condensation cylinder, the water pumping pipe, the driving assembly, the pressure gauge and the adjusting valve, active collection and forced drainage of accumulated liquid in the pipeline are achieved, the accumulated liquid in the pipeline is actively collected through the liquid condensation cylinder, and forced drainage is achieved through the water pumping pipe and the liquid drainage pipe in cooperation with the water pump; the limitation that a traditional condensate cylinder drains liquid depending on pipe network pressure difference is broken through, especially when the pipe network pressure in the middle and later periods of coal bed gas production is extremely low, accumulated liquid can still be efficiently pumped and drained, meanwhile, the solar power generation panel provides stable electric power for the water suction pump, and the problem that a remote well site is not covered by a power grid is solved.

This invention discloses a device and method for mutually promoting and enhancing the gas production and heat exchange efficiency of coalbed methane surface wells, relating to the field of coalbed methane extraction technology. The device includes: a vertical water pump with its inlet connected to a drainage riser installed inside the production well, and a filter installed at the bottom of the drainage riser; a vertical water pump with its outlet connected to the evaporator inlet of a heat pump unit, and the evaporator outlet of the heat pump unit connected to a reinjection interface located at the top of the vertical section of the horizontal well; a water temperature sensor installed at the outlet of the vertical water pump; and a gas extraction pump with its inlet connected to the extraction interface at the top of the production well, and an extraction monitoring sensor installed at the inlet of the gas extraction pump. This invention uses an intermittent circulating heat exchange process to change the coal seam temperature field, improve coal seam permeability and gas desorption capacity, and alleviate the problem of low gas production in the later stages of surface well production.

The invention relates to a backwashing well coal crushing device, and relates to the field of coalbed methane exploitation technology, the backwashing well coal crushing device comprises a coal crushing section located at the bottom end, the top end of the coal crushing section is provided with a coal crushing section, the coal crushing section is relatively communicated with the interior of the coal crushing section, the top end of the coal crushing section is provided with an oil pipe, and the oil pipe is communicated with the interior of the coal crushing section. And the interior of the oil pipe is relatively communicated with the interior of the coal crushing section. The device has the effects of cleaning sediments such as large-particle coal briquettes in a shaft, reducing the influence on underground drainage and mining equipment and prolonging the pump inspection period.

The application discloses a multi-working mode coordinated exploitation well pattern and an exploitation method thereof, and belongs to the technical field of coal bed gas exploitation. The exploitation well pattern comprises a first horizontal well and a second horizontal well, the first horizontal well and the second horizontal well form a communication channel in a target coal bed, and the communication channel is used for selectively accelerating extraction of coal bed gas or serving as a reaction channel for underground coal gasification; and the exploitation well pattern further comprises a multifunctional well, which is communicated with the communication channel. The application constructs a multi-working mode coordinated exploitation well pattern of "double horizontal wells + multifunctional well", realizes the collection of monitoring production parameters, gas production and extraction, injection of carbon dioxide reaction slurry and solidifying fluid in the multifunctional well, realizes the cooperation of CO2 filling, reinforcement, sealing and storage, and solves the problems of lack of special carbon storage channels and difficulty in multi-technology cooperation in the prior art.

The invention belongs to the technical field of coal bed gas exploitation, relates to a self-energizing activated drainage gas recovery process, and introduces a self-energizing technology and a fracturing exploitation technology. In other words, before the self-energizing activator is injected, the fracturing technology is adopted to exploit the coal seam, high-pressure liquid or gas is injected into the coal seam, the coal seam is fractured, cracks are opened, and new cracks and channels are created. The self-energizing activator can increase the permeability of the coal bed, improve the pore connectivity, increase the release rate and collection efficiency of the coal bed gas, increase the quantity of the collected coal bed gas and reduce the waste of coal bed gas resources.

This invention discloses a coal seam fracturing method coupled with liquid nitrogen and a static fracturing agent. First, frozen static fracturing agent particles are prepared using liquid nitrogen. These particles are then injected into the borehole along with the liquid nitrogen. Due to the low temperature and gradually increasing pressure, the liquid nitrogen drives the coal seam to generate and expand fractures. The frozen static fracturing agent particles flow into these fractures along with the liquid nitrogen. After liquid nitrogen fracturing, as the coal seam temperature gradually recovers from the influence of geothermal activity, the frozen static fracturing agent particles begin to dissolve. At this point, the static fracturing agent reacts chemically with water, expanding in volume. This expansion forms a static fracturing agent expansion zone within the fracture, performing secondary expansion fracturing. Simultaneously, the expansion zone supports the fracture, preventing it from closing due to geostress, thus completing the coal seam fracturing. This method not only achieves efficient coal seam fracturing but also effectively supports the fractures, reducing the likelihood of subsequent closure and ultimately improving the efficiency of coalbed methane extraction.

The application discloses a coal-rock interface stress testing method and device influenced by gas pressure, and relates to a device composed of a counterforce frame, a hollow piston rod, two piston cylinders, a gas circuit and a plunger pump. Coal samples and rock samples are respectively placed in the two piston cylinders and assembled with the two ends of the piston rod. The hollow piston rod communicates the inner cavities of the two piston cylinders, simulating the boundary conditions that the displacement amount and the pore pressure of the coal-rock interface are the same. The counterforce frame can apply load to the combination of the coal-containing piston cylinder, the piston rod and the rock-containing piston cylinder and constrain the overall deformation thereof, simulating the constraint condition of the overburden strata on the coal seam. The application can measure the strain values of the piston rod and the counterforce frame in the process of the change of the gas pressure, calculate the pressure change of the end surface of the piston rod, represent the change of the normal stress of the coal-rock interface, and make up the technical blank of the coal seam boundary stress measurement in the process of the coalbed methane extraction or the coal seam carbon dioxide storage.

This utility model discloses a coalbed methane extraction device, including a coalbed methane conveying pipe and a coalbed methane extraction pipe. A filter box is located at the junction of the coalbed methane conveying pipe and the coalbed methane extraction pipe. Sealing rings are fitted between the filter box and the coalbed methane conveying pipe, and between the filter box and the coalbed methane extraction pipe. A coalbed methane filter screen is inserted and installed in the middle of the filter box, forming a detachable structure within the filter box. A support assembly is used to support and fix the coalbed methane conveying pipe and the coalbed methane extraction pipe. This coalbed methane extraction device is easy to assemble and position. Furthermore, the support assembly provides stable support for the pipeline. The pipeline is fitted with an elastic buffer strip, which provides cushioning protection when the pipeline vibrates during transport. The coalbed methane filter screen installed in the filter box can also filter solid impurities in the extracted coalbed methane.

The present invention discloses a high-stress, low-permeability coal seam permeability enhancement system and method, relating to the field of coalbed methane extraction. The system includes: a vibration subsystem for collecting stress values of the coal seam and, when the stress values of the coal seam reach a set condition, releasing stress in stress-concentrated areas of the coal seam to break the stress equilibrium state of the coal seam; a fracturing subsystem for hydraulically fracturing the coal seam after breaking the stress equilibrium state of the coal seam, thereby forming multiple cracks within the coal seam; and a heat injection subsystem for, after hydraulically fracturing the coal seam, using ferromagnetic oxide nanoparticles as a heat carrier to enhance the permeability of the coal seam based on the magnetothermal principle, thereby pyrolyzing the coal seam. The present invention combines vibration with hydraulic fracturing to effectively release stress and pre-induce cracks in the coal seam. It also uses ferromagnetic oxide nanoparticles as a heat carrier to enhance the permeability of the coal seam based on the magnetothermal principle, thereby reducing damage to the coal seam, improving the accuracy of the pyrolysis and permeability enhancement of the coal seam, and reducing the risk of environmental pollution.